fix(mm): 修复fat文件系统的PageCache同步问题

kernel/src/filesystem/fat/fs.rs

@@ -1391,17 +1391,44 @@ impl IndexNode for LockedFATInode {
         buf: &mut [u8],
         _data: SpinLockGuard<FilePrivateData>,
     ) -> Result<usize, SystemError> {
+        let len = core::cmp::min(len, buf.len());
+        let buf = &mut buf[0..len];
         let mut guard: SpinLockGuard<FATInode> = self.0.lock();
         match &guard.inode_type {
             FATDirEntry::File(f) | FATDirEntry::VolId(f) => {
-                let r = f.read(
-                    &guard.fs.upgrade().unwrap(),
-                    &mut buf[0..len],
-                    offset as u64,
-                );
-                guard.update_metadata();
-                return r;
+                // log::debug!(
+                //     "read_at len: {len}, offset: {offset}, file_size:{:?}",
+                //     guard.metadata.size
+                // );
+
+                let file_size = guard.metadata.size;
+
+                let len = if offset < file_size as usize {
+                    core::cmp::min(file_size as usize, offset + len) - offset
+                } else {
+                    0
+                };
+
+                if let Some(page_cache) = &guard.page_cache {
+                    let r = page_cache.read(
+                        offset,
+                        &mut buf[0..len],
+                        |file_offset: usize, buf: &mut [u8]| {
+                            f.read(&guard.fs.upgrade().unwrap(), buf, file_offset as u64)
+                        },
+                    );
+                    return r;
+                } else {
+                    let r = f.read(
+                        &guard.fs.upgrade().unwrap(),
+                        &mut buf[0..len],
+                        offset as u64,
+                    );
+                    guard.update_metadata();
+                    return r;
+                }
             }
+
             FATDirEntry::Dir(_) => {
                 return Err(SystemError::EISDIR);
             }
@@ -1419,18 +1446,30 @@ impl IndexNode for LockedFATInode {
         buf: &[u8],
         _data: SpinLockGuard<FilePrivateData>,
     ) -> Result<usize, SystemError> {
+        let len = core::cmp::min(len, buf.len());
+        let buf = &buf[0..len];
         let mut guard: SpinLockGuard<FATInode> = self.0.lock();
+        let page_cache = guard.page_cache.clone();
         let fs: &Arc<FATFileSystem> = &guard.fs.upgrade().unwrap();
 
         match &mut guard.inode_type {
             FATDirEntry::File(f) | FATDirEntry::VolId(f) => {
-                let r = f.write(fs, &buf[0..len], offset as u64);
-                guard.update_metadata();
-                return r;
+                if let Some(page_cache) = page_cache {
+                    let write_len = page_cache.write(offset, buf)?;
+                    let old_size = guard.metadata.size;
+                    guard.metadata.size = core::cmp::max(old_size, (offset + write_len) as i64);
+                    return Ok(write_len);
+                } else {
+                    let r = f.write(fs, &buf[0..len], offset as u64);
+                    guard.update_metadata();
+                    return r;
+                }
             }
+
             FATDirEntry::Dir(_) => {
                 return Err(SystemError::EISDIR);
             }
+
             FATDirEntry::UnInit => {
                 error!("FATFS: param: Inode_type uninitialized.");
                 return Err(SystemError::EROFS);
@@ -1854,6 +1893,35 @@ impl IndexNode for LockedFATInode {
     fn page_cache(&self) -> Option<Arc<PageCache>> {
         self.0.lock().page_cache.clone()
     }
+
+    fn read_direct(
+        &self,
+        offset: usize,
+        len: usize,
+        buf: &mut [u8],
+        _data: SpinLockGuard<FilePrivateData>,
+    ) -> Result<usize, SystemError> {
+        let mut guard: SpinLockGuard<FATInode> = self.0.lock();
+        match &guard.inode_type {
+            FATDirEntry::File(f) | FATDirEntry::VolId(f) => {
+                let r = f.read(
+                    &guard.fs.upgrade().unwrap(),
+                    &mut buf[0..len],
+                    offset as u64,
+                );
+                guard.update_metadata();
+                return r;
+            }
+
+            FATDirEntry::Dir(_) => {
+                return Err(SystemError::EISDIR);
+            }
+            FATDirEntry::UnInit => {
+                error!("FATFS: param: Inode_type uninitialized.");
+                return Err(SystemError::EROFS);
+            }
+        }
+    }
 }
 
 impl Default for FATFsInfo {